Multi-exponential signal decay from diffusion in a single compartment

Multi-exponential decays in diffusion experiments are typically fitted to sums of exponentially decaying components; often this is taken as evidence for spins in multiple distinct compartments. Here we examine the signal decay due to diffusion in a single cylinder, for short diffusion times (lightly restricted). The signals are well-modeled by a sum of two exponentials, despite the single compartment housing the spins. The results agree with a previous theoretical examination of the problem. The implication for biological systems is that multiple decay signal components may not correspond to multiple physical compartments.